Disinfectants are commonly used when cleaning surfaces to kill micro-organisms and reduce the possibility for infections. Quaternary ammonium chlorides (commonly referred to as “quats”) are one of the most prevalent active pesticides used in disinfectants. The labels on disinfectants describe how to mix them for use and to apply them to surfaces by either saturating the surface or using a wiper, towel, sponge, or other substrate.
Quats are also commonly used as the active ingredient in sanitizers. By definition, “sanitizers” use a lower concentration of quat compounds than are used in “disinfectant” solutions. Typically, a sanitizer will only have 200-400 ppm of a quat in solution while a disinfectant will have about 600-3000 ppm of a quat in solution. As such, sanitizers are safe for cleaning surfaces used in food preparation (e.g., restaurants and kitchens), while disinfectants are used to clean surfaces in hospital environments.
The U.S. Environmental Protection Agency (EPA) requires that kill claims be substantiated by efficacy studies for the mixed liquid, but not for the liquid that is expressed from a dry wiper that is wetted by the user (rather than pre-saturated by the manufacturer). The problem is that a wiper may deplete 10-60% of the active quat from the disinfectant, depending on the materials making up the construction of the wiper. The active quats are adsorbed on to the surface of the wiper substrate. For example, cotton towels are prevalently used because of their absorbency. However, cotton towels deplete 60% from active quat from a quat-based disinfectant solution introduced to such a towel. Similarly, polyester wipers deplete around 10% of the quat from the disinfectant solution introduced into such a wiper. This reduction of active quats in a disinfectant solution decreased the effectiveness of the solution to kill harmful micro-organisms. The same type of problem is also encountered with sanitizer solutions.
For example, for a wiper or other substrate to be considered “disinfectant stable”, the substrate must be capable of expressing 90 to 110 percent of the active disinfectant that has been introduced to the wiper from a disinfectant solution. Specifically, for a wiper to be considered “quat stable”, that substrate must be capable of expressing 90-110% of the quats that are introduced to the substrate from the a quat-based disinfectant solution.
Pre-saturated wipers solve this problem by compensating the quat concentrations during the manufacturing process to be consistent with the label. As used herein, the term “pre-saturated” in reference to a wiper, refers to wipers that are saturated by the manufacturer with the desired liquid and delivered to the user in a wet format. However, for products that are delivered to the customer as a dry substrate to which the customer adds their own disinfectant solution, the level of quats in disinfectant solution cannot be increased. In such instances, the customer must rely on the substrate to release 100% of the quats from the substrate after the solution has been added to such a substrate.
Some have addressed this problem by taking advantage of the positive charge of the active quat ion in solution. For example, some have imparted a positive charge to the surface of substrates to repel the positive quat ions in solution. In the field of wipers for use with sanitizers, U.S. Pat. No. 6,667,290 to Svendsen uses an adhesive binder that is either positive or neutrally charged to give the article an overall positive charge to repel quat compounds in a sanitizer solution. It is also contemplated that a positively charged surfactant may also be used on such an article. However, such a solution looses its effectiveness with higher concentrations of quat ion as are present in disinfectant solutions.
Additionally, wipers currently available for use with disinfectants and/or sanitizers that address the problem of decreasing quat effectiveness are generally not stable in bleach solutions. In the same way as experienced with quat solutions, the active disinfectant of bleach solutions also adsorbs to untreated wiper substrates. This is problematic for most end users due to the frequent use of bleach solutions to disinfect or sanitize a surface. Even those who use quat solutions in some circumstances will often use bleach solutions in other circumstances and would like to use the same wiper product.